It could be a permissions issue. Go to your user Library (substitute your own name for 99jon)
Macintosh HD >> Users >> 99jon >> Library >> Application Support >> Adobe
The easiest way to get to your Library is to launch Finder and on the menu click Go whilst pressing the Optn (Alt) key and then choose Library. By default the Library is hidden unless the Alt key is held down.
Click on (highlight) the Adobe folder and press Cmd+i to bring up the info dialog. Ensure you have read & write permissions. If not, click the padlock icon and change. Also check the permissions on the Lightroom and Develop Presets folders in the same way.
Click image below: